A number of substituted pyridine compounds, both natural products and synthetic compounds, have been shown to exhibit dopamine .beta.-hydroxylase inhibitory action and have been employed as antihypertensive agents. See for example; Tanabe et al., U.S. Pat. No. 4,009,077 on phenopicolinic acid natural products, Umezawa et al., Great Britian Patent Specification No. 1,246,727 on fusaric acid natural products and Kuhnis et al., U.S. Pat. Nos. 3,914,239 and 3,998,955 on synthetic substituted pyridine-2-carboxylates.